1. Field of the Invention
The present invention relates to a lamp unit of a vehicle headlamp, and particularly, relates to a projector-type lamp unit that uses a light-emitting element as a light source.
2. Related Art
In recent years, even in vehicle headlamps, lamp units that use a light-emitting element, such as a light-emitting diode, as a light source have been adopted.
For example, Patent Document 1 discloses a so-called projector-type lamp unit including a projection lens arranged on an optical axis extending in the longitudinal direction of a vehicle, a light-emitting element arranged so as to face upward behind a rear focal point of the projection lens and in the vicinity of the optical axis, and a reflector arranged so as to cover the light-emitting element from above and to reflect the light from the light-emitting element forward toward the optical axis.
In such a case, in the lamp unit disclosed in Patent Document 1, a mirror member that has an upward reflecting surface that upward reflects a portion of the reflected light from the reflector and has a front end edge formed so as to pass through the rear focal point of the projection lens is provided between the reflector and the projection lens. A portion of the reflected light from the reflector is reflected upward by the mirror member, thereby forming a light distribution pattern for low beams that has a cut-off line as an inverted projection image of a front end edge of the upward reflecting surface at its upper end.
Moreover, Patent Document 2 discloses a projector-type lamp unit in which, as the upward reflecting surface of the mirror member, a region located nearer the self-lane side than the optical axis is constituted with a first horizontal plane including the optical axis, and a region located nearer the opposite-lane side than the optical axis is constituted with a middle slope extending obliquely downward from the optical axis, and a second horizontal plane extending parallel to the first horizontal plane from a lower end edge of the middle slope.
[Patent Document 1] JP-A-2005-166590
[Patent Document 2] JP-A-2006-114274